SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e9b4712b5e80984282f8f835c754e611a65cde996bea630a48b3942fd4240f59' 
  AND token = '6rYY7wihMrn1CqGwxQPuyR7mnjlbjXByUNckT2dLlFE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00016

JSON explain

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