SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7021a71fc9c247333fa5240a2d2c68b0742c394d97433bf26695c38d758e524f' 
  AND token = 'g61Kj18VNTLcvP/V6ph68cQBtcemqtO+pZwDn7qqwzE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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