SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c6ee3995dea7c582512974f491e9424bb3dd6e259731d22a832bacbbdb72cdc0' 
  AND token = 'nqrfeUo29+WcYVhtOb9plsTKQpRV3ix7Osoq7X7Vg3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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