SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87d8c4bd7b3f6629516999c6d624fa96d64f44f0b48d4e00385c4ed1af7bbc1e' 
  AND token = 'XDGWKrXpR1MJClZ36TY5QOvXG3RKJGSRNyQHTE+7kBY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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