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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ec5e2f27f15b229ea61ae1dea1b9b0bb4794ef94fa5c7f567b49bd47a595811' 
  AND token = 'mk7S0vAJTSrqYMU/HzQo1GJkqK87KlJDUoTby/N+40g=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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