SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8456c88268d5b6728d3bc6dd6011913e78259c91afdfdd550b3b39a96a4c8162' 
  AND token = 'eUL6k/4Jm+wWfMlcSa87H+fG4o/CvfQsAQYOuqzNghM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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