SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7a3b8950d915fb4f89577b5fa45f06980b21fb92529c52927f8ffe321ee49cc9' 
  AND token = '7hg8RA+tHbS0b97s5NyQPkcdEFktiDmSVfUv+iYu5Gg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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