SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1520d0b1364770162db36a8b99a5419b11994e8237e30f64f8fdfc4faac03527' 
  AND token = '864i7TBd7cckYqDxgl0f/BnAPDPe4DCFlF5f5h2a5Gs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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