SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87539362413a6a522ac9adb80c7305f6386287dc19f083b9f94a8a1676cdf2f3' 
  AND token = '5/iHgintTQBfCvTXTDzO9jtyefXZuBCZg8i6tbbiqWw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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