SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5c6b12753d3f13b8df91d420aeec47bca3e5d32cdfcbf5b7b7392e838bb68333' 
  AND token = '/4wQN0/mZtdTfTVPd0hY9Cr2KRObKJ59Gu6jk+B0go4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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