SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3cccb7f562fb6f658fbd45bc273470a4376aa853119a4c00c9228020f8b243d8' 
  AND token = 'qkzF+ShoVHqPZlZHaXrlpe5iOJGScLhLGfomCkWCquU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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