SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '639622c520676c5182689d6980111eb72fd48b4bdb62d824b38b2164e407b84f' 
  AND token = 'xmY+jIjsqwlEjgiR8f1bhhvV5aWLWjLHKodqHg+oKKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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