SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe9a74e93f9b0526f1cf158e3a5b6d939733da6466618aa0b77f47dd21fa0cf4' 
  AND token = '5YXC8G9+LLkJQ1hV+hTXmYv7xxeRUv7H1cWPd3+Nl/Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00046

JSON explain

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