SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c5ee0b5bceece1674a037c2eda8e85c33d71c92f93794deb740adeb5a8be1f25' 
  AND token = 'h7vqsW/lvC+xHT86VnnprsltAPuXFAa5jGgbMB6bVzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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