SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9243810a958aabab82f14cc41ecc3ef2c6f903cee39b8b026be45843dc29b315' 
  AND token = 'oPAaTQsL4X9PXY9sgO+BKV2ns/wi0hbBH92hs/dHRcw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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