SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f6c77e9457fe99cf2ea7a200da46db68822187b9007ec46e8f151987dcfb91dd' 
  AND token = 'S7NYRTFdOsyZN7SpK4MJaNZM+OeoXL42XSMOjxz/kxk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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