SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f29716d39a6d115318a80a4d7889c9d8be0bbe457ca5443b0793e0efde227e84' 
  AND token = '0m0epP6RfWL+jOwhxGYgu5nEh9lrhETgfFgpT8jjKrA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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