SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77db6898487c96a27f7af8569df3f81a8fb06ae04fad54d4336b977ae92be5c7' 
  AND token = 'i7LjAMqZYgGJxxDE4ssObf+VgN+wAOWSRn+iJNDmNP4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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