SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ad508871fe21de53ce5973a6cd47a8b4b52536ad0ca9de5fa27b25847f7e37e4' 
  AND token = 'q++gnPfRJiVYACTKkZCkPrzCbffkYEplPKktzfZsrxc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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