SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '236c4e0dae1fe68010d2482e5cbf0789bb6ab51dc4e507d3021bb993393252e4' 
  AND token = 'oSKDFAjKnhilGwTNZbVq1vJ45wQZBTdlAL1CkWnVBRs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00014

JSON explain

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