SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ff83049acae4d4fdd115a3ae1e89884616424bc2fc66100c983bc78e898c253c' 
  AND token = 'eHvyiGlFBBr0gOLMvj/bExt91bI/tMn8lGAJmPHMq9E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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