SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5702bce6893fb56984d2b9c47b289bf04a6ced6af81c281af9a2f44ff34a6640' 
  AND token = '8JKKBBfeZwvVlRr8KiAqhU57B0GvaHkvPXcJ8sPLX7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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