SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9dfa7782e21c128080c018dff90f1ba4cc2f3721b8dff9f4888a2f8051bac90b' 
  AND token = 'NSSriUXZwr+48qIvZR9qmXIjgsNmu6eI/FgFQdSTbFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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