SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'adece3f37f0be769fd0141721a26309574a97285cb0b19b98c28cb37ab0cf51b' 
  AND token = 'b0ef7XoxznOQrR5CwGJhlXPEM4QTXctJmYchQOWItsE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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