SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5405243c773b21b16448224ab2f5665ec923978483f9b6f4cd3027450e23b427' 
  AND token = 'x6S8KmdNP58wQAT3VagwhaGbdZHNcJIQkwVcO5UZQC0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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