SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e2dea1ca4a387e85c0c2ca504eb363228dd046abbdbd5716252090c45562382' 
  AND token = '+IVkxk18LFqyT3b1jQM/xHoQeq3ZHkmSXztZNzODFjk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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