SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9c8fb6011f73f5815961ef3724e097690c3dc82faa412c0933fb36e0519a830' 
  AND token = 'gGgHkraOTskQSYTWgHQc36YN+5A1FqC/Gnnwtkr4lq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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