SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38c881f5de69e50341ead2e9e988ca695d13f08d87fb4ba3974a6bb763081546' 
  AND token = '2KYLdkNDcqHwWTuBqG7CMf0TM8CFuzVlO8+YJ2JeAfQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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