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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e39d9b6212922fcb121a8e339a7f5547dc3e30c5ff3a11d8fff8d9d0aa29c7ac' 
  AND token = 'ElJKoBEmddq/D9aZFSBRgw82L0lscLUt9V0Tfxairbs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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