SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1753dd13a39ca537a8024be993db648644ab5a9285642f07a559587422c3fb81' 
  AND token = 'iJr50XWR0PpvH+Z0HjVwRPlFd+M/5TSVK0nGqXwfQl8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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