SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4604a33fcbe82c8b75be9362faa3cd127639f1d34a7a57058155ad4714a7798e' 
  AND token = 'rYkRszKHCYVfEJ1nM5FijuIz0YG+3UMf+nYxQaK8OFg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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