SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e43f40c543d916aaa2a9f16dcd0c2d671f656225047b94072a5111056f7fdb2' 
  AND token = 'hZ7zsS9hLVpl2j319bZ8+XYgTfEjMki7DKWtX0n/Awk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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