SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0737b9e650355d70acbf4fd6e5389579142d39fa36189fc2a4969fcdbb4b2bce' 
  AND token = '+gLlfQIWrD5Xa4TqosjTG8W8mE6sEHBwhuP6V4Bc6hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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