SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dc942ade3773786bda311883aa47aaf791c3916a2c9325f1278c1670ebc3732e' 
  AND token = 'L9a6Qi8T8XW1NSl3V7aGnDHXeHBBW5+nFRK0BndbnhU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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