SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c309138e9376b928405406f705869ffec3bfbdd27110536b06c10ae3f97e55f2' 
  AND token = 'gYcc/PRZzGci54TzygV6i7RUfwrj0B5BjvX3quS0qTk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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