SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6be43a646aba62896f1345e76b3314aa57741ae550de2219203397bf9bc5e60' 
  AND token = 'MAJ32W+aygDE/IbwCFlEsujXMI/u4FeK4jBDVOuOZQY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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