SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a591d50c473d6a9ab2dc64821d4afcf8331efb120d3c49c08ee826e505c07c07' 
  AND token = 'ZzjwHRtSCL0DsrLTw5gUZbwlHnuqtDf7+AaDsCbyXw0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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