SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'af4b9999257c81ee2c71e6a6052681070f88adab38c8969e50e1546dfb976c58' 
  AND token = 's6c65iz9uADx78ihaUiGG7hGYWEZOnampm4KUHer/Dw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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