SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '39a70d7af1b6c2a164541d57775cdf3119ed56920f822142531f79a44c204f4c' 
  AND token = 'wvWjhtl7UO7pjNccqfupS5Ikz3OF8/z21HjP1KtigL4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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