SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4849cc479a5116d0783f80e0042f4a5d68e0e5ae63b590f3fb61ae929ee47abd' 
  AND token = 'w7wJoAVNWmXoOA7m1eDJtq2PO1EonnzkjGZ2xKlh3qk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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