SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e3d693448009a834839def58252ae5e23214d1938bd99858483b36cb822a30a7' 
  AND token = 'PSwgbmpf0yPm1lrMCbnnrZSJdOeVrjgXbm8tFh0rTKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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