SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9bce3809b5a8cd402891252279dd95c163d4ff54746a2093b3fab8f4e115adaf' 
  AND token = 'MrMs9CbINvafrvGdosiq9dr/Pk3dsVNS5FX3PMNu5Zk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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