SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '75bbd799066ba527182ed7528eaf46f4bf4e31cfefc4da1035ec8ec5300e653b' 
  AND token = 'uydz0bRKy/f2QGJgPkfdqjGEV/XCIFvBogY8aW5XG5o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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