SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6268002401364a2e7bcf883868bf99092b1650ff00c4f2de2a2c95698488045f' 
  AND token = '9DO+mocg/YULAZD3p/shZxLTYCBMyvh8dhzpPXcGxLo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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