SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc6f02ae226e0e0d76b2b3600cb436bdf641f9d6f0029272b6390adb8d0b8edf' 
  AND token = 'afy/pmJ8UKMeKsRNp7N49TniZ5fgL5E3bOSwBTmmXQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00010

JSON explain

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