SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5dc49e35d47e489eda56fa3f91cde29722ae33f7cef66a86a643b65373151fb3' 
  AND token = 'H+VRIxduUBWvgFfPjePjIvBkiBrzCd8QFvTbUKd36Yk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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