SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e4c256f3e7bd011bebeb2ec05f912403e1fa38a8090f3c91521d60771a7db8c' 
  AND token = 'M2Ks4/sa4zS2AjdIDqytNVaalJjHF/DMgbHd3dMkKoY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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