SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a9eda93e3f779306cdae375d0391c978614a01e858e05860d177450c49a4837' 
  AND token = 'yzjIt9/353rCdKHw5St7GIPKNhhxv8mJmyRa07tOKAU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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