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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b5710d950ee4ac6ddf526f684276bc8a2e4fb9c980029150175de5b9895b49f0' 
  AND token = '64XsZ5LcnuEuyQnL4k9vWtaL35hlt8dGWykTIWeRYUo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}