SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe44f92806712075f3b6111bf34c29408db884823bfdceda0e3c69976bf35da8' 
  AND token = 'GxtjsLXWBuS6t2OT4AiTwnIgBlbvh/MAu6sxulLZfGo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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