SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1c9c94493e1832b60f075366f316c456ef98c653d9bfc03b43aa7b982f6ddbb8' 
  AND token = 'M9OQn8hV3z/tPZElmqwnW51TpmKWXhpjwpYL54Ln0EI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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