SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dd194b6f2ec83a4103e5a25cfa343f1820fc995ab2030c0555e0c269e78b5dc3' 
  AND token = 'a3YxiJ/LRncFwgTIP9G6VxFZ2PwxrEpPvQp4RPWhquQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00048

JSON explain

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