SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '56b3ad1da4d123aa92d3e708a25e2cf3fd73be60bbab9f7c8c286a08cba5eb56' 
  AND token = '4nbDil+g9R7emnLeTU3+16pLabW0rMMAjsutj5UJzm0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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