SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fb0f59eb3470562dc10128640f41503b7afbb6a856d5cae3bf96213e5f0cd69e' 
  AND token = 'LwLq09XismTkp0Y3JZgpLzxdTvjQy7W9DMtHWwVXaRE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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