SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eb6804cc83624865f76e4c95a92ef0629cac80d41792c23a13e34811f0b14390' 
  AND token = '6EIwXDMCZSy2LdeoWlnGJNkP1AOKZQQ1qZUmUGo/OYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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