SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '897ae616d21f4513a21604bb8b1027ad817591fffba52277dcb3d5e3946699b4' 
  AND token = 'rU/Rj7Z9JFmb2NKznbY4F3Y/SlyiaqOFddj+vZ1j2TA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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