SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9b576ab0dedbfb1d9d3f24daf86731a30367bec1dc33f9800c9f8e1699de41b' 
  AND token = 'uIR1BphYGHRX5OjqQBQPpvmeEN2OgPTdqCFj1IlPWqg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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