SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f7936eee9d06eaa6e9a852266f94f083b8f0c9dea6a0ead2ba9dcb42dcb4f2fe' 
  AND token = 'sItkwnQnR93zQbRw8a+3NRI5EwNVJk/uL5OHHgnJTh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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