SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1b90975236ac61ab05fca61688aafe8482b9e6673920988e117cf33e9ebb2b86' 
  AND token = 'WnRQOOHw1jTcGJaESF7419DRGlZyjpZ/EKMFLgSHGcI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00041

JSON explain

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