SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b38496a7fe948e157867e60df6cb0175142323652a04208a5afa81d6b9c27bfc' 
  AND token = 'J5eMMrwg1Ppocfpeezr2ySMSXCmMn/nreczJPXXOUQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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