SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '19c46195ee333217ee597efebc4e3b373eacc57b45adaf0b48115ff6844ba019' 
  AND token = 'UCGsmvMN38SwVyXFrADFdypOr13IV9TBwT0Qk6VNR/k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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