SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e7afb57edec5e7675e2d8057d22db12afa1a340646eda67076dbeafa31883fed' 
  AND token = '4xYd17EQHuGqU9KQTOzFuaW5cCGU83LqeYQicTOxsdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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