SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c1450b950e397ebf816da676da8b54e9a1998792660614af05cde0250288641d' 
  AND token = 'sxyNH8aIG2YmumiGOFH8OKPhTxYVK+fF/cW+NCzY1ws=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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