SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '375ded792199948dbe75542111a3132adacb9e8dbf44b7dd70fecb091822ad75' 
  AND token = 'cKmsyi5uHPH8Pb6e2wUVWJcnUENIIaAO6cRZHOBRa3I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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