SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9decd63848e1b6f5a611d9d62064e89d7fb39e7d011a7492b927c826e47408cd' 
  AND token = 'r6rlJYqaeJDEn9CHl8T8w3ZWEYqyTRdEHndBCYfRsxY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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