SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f67db03054dac3e741e962822ef62c26f18a6d3550c32be2c5ea202beaee9610' 
  AND token = 'gdoNAvHT/VOxWZVwR+n2Ck/2Ejz3Zuk90h/2j4hya1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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