SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6e9fa659fad1bd11f96694f70da68b2bb31903dc525014488fc749a21e43a236' 
  AND token = 'fOtkNJhmdcmQiJbGEXe01Cr9vbMmpOFyVmL8PzYrcKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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