SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a7506cecfcf18a5c2e639b16ae375e0887c4bd3197f6ccae41161d21775a749' 
  AND token = 'U79XPgcAyzYZ4YPWIpPEyiMQNYIhCRxpTWJGcTNuN2E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}