SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '00392ab97140ffa6e259cc01f9fcc3fa354c2b7fc9c9e3030eb451272faa135a' 
  AND token = 'LM+3yL9WDkcrzskVJ3rWQjd/IUJnscYxnEDxUWfdigQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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