SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '157ccb676b1433b43a8250a39937a7dc64e54471c03de948b3e263dac01a7e3d' 
  AND token = '+i50x1zLloE8zCaSk/BZpeq3YKd1qHGv345KOpDA32U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}